Reinforcing cup-type grinding wheels

ABSTRACT

The disclosure illustrates the reinforcement of a cup-type grinding wheel which has a peripheral surface tapering from a grinding face. A pair of wheels are positioned face to face while a tape comprising a plurality of strands of filamentary material is wound around the grinding wheels with a portion of each turn on one cup and the remaining portion on the adjacent cup. The wound tape is saturated with a curable resin and the wheels are urged apart by a spring to maintain the tape in tension. After the resin is cured the tape that extends between the junction of the grinding faces for the wheels is cut off to produce two reinforced cup-type grinding wheels.

United States Patent Peterson June 17, 1975 REINFORCING CUP-TYPE GRINDING WHEELS [75] inventor: George N. Peterson, Grafton, Mass. [73] Assignee: Dresser Industries, Inc., Dallas, Tex. [57] ABSTRACT The disclosure illustrates the reinforcement of a cup- [22] lune type grinding wheel which has a peripheral surface ta- [Zl] Appl. No.: 149,192 pering from a grinding face. A pair of wheels are positioned face to face while a tape comprising a plurality of strands of filamentary material is wound around the [52] US. Cl 51/209 R grinding wheels with a portion of each tum on one [5 [1 Int. Cl 824d 5/00; 824d 7/00 58 m is h I204 206 R 206 NF cup and the remaining portion on the ad acent cup. l 0 512O9 R The wound tape is saturated with a curable resin and the wheels are urged apart by a spring to maintain the 56 R f d tape in tension. After the resin is cured the tape that l 1 e erences extends between the junction of the grinding faces for UNITED STATES PATENTS the wheels is cut off to produce two reinforced cup 2,800,754 7/1957 Robertson 5l/209 R type grinding wheels. 3,43l,687 3/l969 Fischer et all .7 51/206 NF 0 3 Claims, 3 Drawing Figures o I2 I f [I M28 46 f H I A i r38 34 1/9 55.: 26

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a N W E 5 6M 3 GEORGE N. PETERSON 70 BY 7'1 M.

ATTORNEYS.

REINFORCING CUP-TYPE GRINDING WHEELS The present invention relates to cup-type grinding wheels and more particularly to a method and appara tus for reinforcing this type FIGS. wheel.

In recent years there has been a tendency toward the operation of the cup-type grinding wheels at ever increasing R.P.M.s to improve their cutting efficiency. The increased operating speeds in some cases are so great that the grinding material has insufficient internal strength to resist the centrifugal forces which tend to make it fly apart.

To solve this problem it has been proposed to reinforce the periphery of this type of grinding wheel. One such method of reinforcement is to wind a number of turns of a continuous strand of filamentary fiberglass material around the peripheral surface of the grinding wheel and it is saturated with a curable resin to form a reinforcing band for the periphery of the wheel.

It has been found that with this approach it is difficult to maintain a uniform tension in the strands of fiberglass through each and every turn. This causes some turns to carry more tensile stress than others, thereby lowering the effectiveness of the band in resisting the centrifugal force acting on the wheel.

Therefore it is an object of the present invention to uniformly and effectively reinforce the periphery of a cup-type grinding wheel.

In one aspect of the invention the above ends are achieved by a method which comprises the steps of positioning the grinding faces of a pair of cup-type grinding wheels face to face. A number of turns of at least one strand of filamentary material is wound around the peripheral surfaces of the wheels and saturated with a curable resin, said strand being wound in a direction generally nonparallel to the plane of the grinding faces so that a portion of each turn is on one wheel and the remaining portion on the other wheel. The wound strands are urged apart with a substantial force while the resin cures to maintain the strands in tension.

In another aspect of the invention the above ends are achieved by apparatus which comprises an arbor over which a pair of grinding wheels are telescoped so that their grinding faces oppose one another. The wheels are yieldably urged away from one another with a substantial force and an adjustable limiting means maintains the wheels in a first position while the strands of filamentary material are wound around them. The adjustable displacement limiting means is then released to permit the yieldable urging means to displace the wheels away from one another so that the turns of the strand are held in tension.

The above and other related objects and features of the present invention will be apparent from a reading of the description of the disclosure shown in the accompanying drawing and the novelty thereof pointed out in the appended claims.

In the drawing:

FIG. 1 is a diagrammatic view of apparatus used to reinforce the periphery of a pair of cup-type grinding wheels; and FIGS. 2 and 3 are views of the cups of FIG. 1 shown in successive stages in practicing the method of the present invention.

Referring to FIG. 1 there is shown a pair of cup-type grinding wheels and 12 which have grinding faces and 22, respectively, and annular peripheral surfaces 11 and 13, respectively, tapering from the grinding faces. Grinding wheels 10 and I2 have internal openings l4 and 16, respectively. telescoped over an arbor 18 so that their grinding faces 20 and 22 are positioned in opposition to one another and spaced apart by a spacing disc 24. Grinding wheel 12 abuts a flange 26 on arbor I8. A spring 28 acting on interior recesses 30 and 32 of grinding wheels I0 and 12 urge them away from one another with a substantial force. An adjustable limiting means comprises a nut 34 threaded onto arbor 18 to hold the grinding wheels in position against the force of spring 28.

Arbor I8 is connected to and driven by an output shaft 36 ofa gear box 38. Gear box 38 has an additional output shaft 40 and an input shaft 42 which receives a driving input from a shaft 44 of a suitable motor 46. Shaft 40 connects through a right angle gear box 48 to a drive shaft 50 which drives a cam 52 via another right angle gear box 54. Cam 52 has a follower 56 attached to an arm 60 connected at right angles to an element 62 which is displaced in a suitable slot 64 in a direction parallel to the axis of arbor 18. Spring 58 urges element 62 to the left so that follower 56 is biased against cam 52.

Element 62 has a suitable guide 68 secured to it which forms a guide for a strand 70 of filamentary material, the strand 70 being stored on a suitable drum 72. It has been found that the material used to wind the grinding wheels may take a number of forms, for example, continuous filament fiberglass strands comprised of filamentary fiberglass material, fiberglass roving or yarn. For convenience in winding the drums the strands may be formed in a tape to allow the application of a great number of strands for a given rotation of arbor 18. All these types of materials may be secured from any number of suppliers known to those skilled in the art.

The strand 70 is reeled onto the peripheral tapering surfaces 11 and 13 of grinding wheels 10 and 12 as described below.

Motor 46 drives arbor 18 to rotate wheels 10 and 12 thus causing strand 70 to be unreeled from drum 72 and onto the peripheral tapering surfaces of the wheels. A suitable friction brake 74 retards the rotation of drum 72 so that the strand 70 is wound with an initial tension. The strand 70 is saturated with a curable resin either before the strand is wound on the grinding wheels or after, depending upon manufacturing convenience.

The resin is of the type that has a relatively long curing time, as described below. Resins that cure at elevated temperatures have been found particularly useful for this operation. An example of this type of curable resin is an Epotuf Epoxy Resin mixed with a Versamid No. curing agent in a 70 30% by weight mixture. The Epotuf Epoxy Resin is manufactured by Reichhold Chemicals, Inc., Azusa, California, and the Versamid curing agent by General Mills chemical division. This particular mixture cures at F. for eight hours. It should be apparent to those skilled in the art that a wide variety of curable resins may be selected to give acceptable results for this method.

As motor 46 drives arbor 18 through gear box 38, cam 52 is rotated thereby displacing guide 68 back and forth in a direction parallel to the axis of arbor 18. The gear ratios of the gear boxes are selected so that guide 68 will be in line with one of the grinding wheels for greater than 90 rotation of arbor 18 at which point the guide crosses over to the adjacent cup. This causes the strand to be wound in a number of turns on the cups with a portion of each 360 turn of arbor 18 being on one wheel and the remaining portion of the turn on the adjacent wheel. With the arrangement shown each wheel has the strand 70 wound on its peripheral surface for greater than 90 of its rotation at which point the strand passes to the adjacent cup. The adjacent cup has the strand wound on its surface for the same degree of rotation. The net result ofthis is that the point at which the strand 70 crosses from one wheel to the next is at a different peripheral position as succeeding turns are applied to the wheels. The degree to which the tape is wound on each drum may vary from between 90 to 360. It has been found that a winding of approximately 240 gives acceptable results.

When the wheels are wound with sufficient strand the strand 70 is severed and suitably tucked into the wound strand After the wheels are wound with the saturated resin the nut 34 is loosened, as shown in FIG. 2, so that the spring 28 is free to displace the grinding wheels and [2 away from one another with substantial force. The wound strand restrains the outward displacement of the grinding wheels and as a result is placed under a substantial peripheral tension. It has been found that a spring force of approximately L100 lbs gives acceptable results. However, other force levels may be selected for particular applications. The long curing time of the resin enables the tension in the succeeding turns of strand to be equalized so that each turn uniformly is stressed in response to centrifugal forces on the wheel.

When the resin is cured the nut 34 is advanced to a position where it abuts the face of grinding wheel 10 in the expanded position and then a cut-off wheel 76 is applied to sever the tape 70 at the point at which it crosses from one grinding wheel to the next. The wheels 10 and 12 are then removed from the arbor 18 for use.

The reinforcement that results with the invention described above is highly effective in resisting centrifugal stresses placed on the grinding wheels 10 and 32. Since the wheels are tensioned during curing to maintain a uniform stress, each and every strand contributes uniformly to strengthening the wheel. While the strands are not continuous around the periphery ofthe individual whee], they are bonded to one another around a sufficient portion of the periphery to maintain a highly effective reinforcement. Furthermore, as the grinding faces 20 and 22 are worn away, the reinforcing strands are cleanly cut away at their ends instead of being frayed, as is the case with prior art reinforcing where continuous strands are wound parallel to the grinding face.

While a preferred improvement of the present invention has been described, it should be apparent to those skilled in the art that the invention may be practiced in different manners without departing from its spirit and scope.

Having thus described the invention what is claimed as novel and desired to be secured by Letters Patent of the United States is:

1. In combination:

a cup-type grinding wheel having an annular peripheral surface tapering from a grinding face;

a plurality of discontinuous strands of filamentary material wound in tension around portions of the peripheral surface of said wheel in a direction nonparallel to the grinding face thereof, each strand being wound between and less than 360 of said peripheral surface; and

means for bonding said strands to the peripheral surface of said wheel so as to maintain the wheel in compression.

2. An article as in claim 1 wherein said strands of filamentary material are in the form of tapes.

3. An article as in claim 1 wherein said means for bonding the strands to said wheel comprises an adhesive incorporating a resin curable at an elevated temperature. 

1. IN COMBINATION: A CUP-TYPE GRINDING WHEEL HAVING AN ANNULAR PERIPHERAL SURFACE TAPERING FROM A GRINDING FACE; A PLURALITY OF DISCONTINUOUS STRANDS OF FILAMENTARY MATERIAL WOUND IN TENSION AROUND PORTIONS OF THE PERIPHERAL SURFACE OF SAID WHEEL IN A DIRECTION NONPARALLEL TO THE GRINDING FACE THEREOF, EACH STRAND BEING WOUND BETWEEN 90* AND LESS THAN 360* OF SAID PERIPHERAL SURFACE; AND MEANS FOR BONDING SAID STRANDS TO THE PERIPHERAL SURFACE OF SAID WHEEL SO AS TO MAINTAIN THE WHEEL IN COMPRESSION.
 2. An article as in claim 1 wherein said strands of filamentary material are in the form of tapes.
 3. An article as in claim 1 wherein said means for bonding the strands to said wheel comprises an adhesive incorporating a resin curable at an elevated temperature. 